Membrane proteins: structure - function - methods of analysis

利用天然纳米圆盘的力量***膜蛋白存在于所有生物膜中。它们具有许多基本功能，它们的表面位置使它们成为制药和生物技术工业中理想的药物靶点。尽管它们非常重要，但科学家们仍在努力研究这些大分子在功能上的活性形式，并与实验相兼容。传统上，在体外操作膜蛋白需要使用不能模仿原始生物膜特性的洗涤剂。即使是最温和的也会导致蛋白质不稳定或蛋白质活性的丧失，除了破坏蛋白质-蛋白质的联系。******苯乙烯-马来酸（SMA）脂质颗粒，也被称为天然或SMA-纳米盘，是一种从膜中提取蛋白质的新工具，破坏量最小。在sma -纳米圆盘生成过程中，苯乙烯部分插入脂酰链之间形成一个“手镯”，环绕着一小块脂质双分子层（直径约10-15 nm）。通过这种方法，可以从天然膜中提取和纯化膜蛋白和蛋白质复合物及其天然脂质。除了保存天然脂质环境和蛋白质-蛋白质相互作用的固有优势外，由于这些颗粒稳定且可溶于水，因此可以开发各种各样的应用。***天然纳米圆盘是膜生物学领域的一个令人兴奋的新发展。在这个提议中，我们将以三种不同的方式利用原生纳米片的力量。我们将1)采用基于蛋白质组学的方法来鉴定和分离在洗涤剂中不稳定的新型膜蛋白复合物，2)构建一个sma纳米圆盘文库来鉴定几乎任何给定配体的膜受体，以及3)开发一种方案来快速鉴定任何类型细胞膜蛋白周围的特定脂质。这些应用中的每一个都将为发生在膜界面上的关键细胞过程提供重要的新信息。此外，由于膜蛋白在天然状态下变得越来越容易获得，我们的工作可能会激发制药行业的兴趣，特别是对于以前被认为难以有效制造的膜蛋白靶标，如药物发现等下游应用

Exploiting the power of the native nanodisc***Membrane proteins are found in all biological membranes. They have many essential functions and their surface location make them ideal drug targets in pharmaceutical and biotechnology industries. Despite their great importance, scientists still struggle to study these macromolecules in a functionally active form that is compatible with experimentation. The manipulation of membrane proteins in vitro traditionally requires the use of detergents that fail to mimic the properties of the original biological membrane. Even the mildest ones lead to protein destabilization or loss of protein activity, in addition to destroying protein-protein associations.******The styrene-maleic acid (SMA) lipid particle, also termed native- or SMA-nanodisc, is a new tool to extract proteins from membrane with minimal amount of disruption. During SMA-nanodisc generation, the styrene moieties intercalate between the lipid acyl chains to form a “bracelet” which encircles a small patch of lipid bilayer (~10-15 nm diameter). In this manner, membrane proteins and also protein complexes, together with their native lipids, can be extracted and purified from the native membrane. In addition to the inherent advantage of conserving the native lipid environment and protein-protein interactions, a wide variety of applications can be developed because these particles are stable and water-soluble. ***The native nanodisc is an exciting new development in the field of membrane biology. In this proposal, we will exploit the power of native nanodiscs in three different ways. We will 1) employ a proteomic-based method to identify and isolate novel membrane protein complexes that are unstable in detergent, 2) construct a library of SMA-nanodiscs to identify membrane receptor(s) of virtually any given ligand, and 3) develop a protocol to allow rapid identification of specific lipids surrounding membrane proteins of any type of cell. Each of these applications will contribute important new information to key cellular process that occurs at the membrane interface. Furthermore, since membrane proteins are becoming easier to obtain in their native state, our work might stimulate interest from the pharmaceutical sector, especially for membrane protein targets previously considered too difficult to manufacture efficiently for downstream applications such as drug discovery.**